This invention relates to leg prostheses in general, and specifically to a pylon to be used with a prosthetic foot. The pylon of the invention is characterized by a lightweight, elongated structure incorporating polymer impregnation of superimposed reinforcing laminae maintained in the desired configuration, such that any of a broad selection of prosthetic feet may be attached to the lower end of the pylon.
In addition, the desirable characteristics of strength and flexibility in the pylon member are enhanced by providing a multiplicity of the above-described elongated structures in juxtaposition to each other. This multiplicity of structures provides an interchangeable array from which the wearer may select an appropriate member for a particular activity. In alternative embodiments of the invention, deformable adjustment means, such as one or more inflatable bladders disposed between the aforesaid elongated structures, or other resilient means operatively engaged with the elongated structures, are provided to increase the ease and precision with which the flexibility of the prosthesis may be adjusted. The elongated structures may also be provided in a concavo-convex configuration, to improve or enhance the performance of the prosthesis.
Various types of foot and leg prosthetic devices are known in the prior art. Such devices generally include some form of attachment for coupling the device to the dorsal end of the limb and for extending to the ground to provide body support. Such prosthetic devices, particularly those intended to mount below the knee, are now frequently fabricated as an assembly having a leg region and footlike region, with some form of pivot therebetween so as to allow the foot portion to assume various angles with the leg portion and vice versa, as the wearer walks or goes through conventional motions. Devices of this general type are shown in U.S. Pat. Nos. 2,379,538, 3,400,408, 4,007,496, 4,089,072, and 4,161,042. In general the leg and footlike portions are usually rigid members.
My invention, in contrast, is compatible with a range of prosthetic feet and enhances the performance of such feet. Examples of such prosthetic foot devices include U.S. Pat No. 2,075,583 to Lange, which incorporates a rubber form mounted in operative relationship with a rigid metallic core, and U.S. Pat. No. 4,645,509 to Poggi, which teaches a prosthetic foot incorporating a monolithic keel or beam of relatively massive proportions intended to react to the load of an amputee's body during walking, running, jumping, and the like and to release the resultant stored energy to create foot lift and thrust complementing the amputee's natural stride.
These and other prosthetic foot devices have significant deficiencies, however, providing an opportunity for improved performance when the device of my invention is utilized; specifically, the component parts of the aforesaid foot prostheses, as in Lange, are too heavy and too rigid or, as in Poggi, are too massive and monolithic to respond properly to the nuances of stress-response gradients characteristic of the human foot.
These deficiencies are overcome to at least some degree in U.S. Pat. No. 4,547,913 for my invention relating to a "Composite Prosthetic Foot and Leg", and U.S. Pat. No. 4,822,363 for my invention relating to a "Modular Composite Prosthetic Foot and Leg". Those patents disclose certain concepts relating to a prosthetic foot characterized by a lightweight, unitary structure incorporating polymer impregnation of superimposed reinforcing laminae maintained in the desired configuration.
In addition, my aforementioned patents disclose interchangeable foot, heel and ankle portions which may be permanently or demountably associated with each other whereby the portions can be readily exchanged with correspondingly constructed portions. This exchangeability permits size adjustment or accommodation of different spring rates to suit the size of foot of the amputee or the stride and weight of the amputee, yielding an almost infinite range of combinations of spring rate and size to the amputee, and allowing a natural stride and resilience of gait which has not been obtainable by prior art prosthetic devices.
Some of the benefits of my inventions disclosed in my aforementioned patents inhere in the interchangeable, lightweight, laminar construction which provides selectable degrees of strength and flexibility in a given structure. My present invention enhances and accentuates those same benefits, and in addition, provides at least some degree of those benefits to wearers of conventional or non-laminate prosthetic feet.